Oct-4 Enhanced the Therapeutic Effects of Mesenchymal Stem Cell-Derived Extracellular Vesicles in Acute Kidney Injury

Abstract

Background/aims: Acute kidney injury (AKI) is a common clinical condition that can lead to chronic kidney failure. Although mesenchymal stem cell-derived extracellular vesicles (MSC EVs) are regarded as a potent AKI treatment, the mechanisms underlying their beneficial effects remain unclear. Oct-4 may play an important role in tissue injury repair. We thus hypothesized that oct-4 overexpression might enhance the therapeutic effects of MSC EVs in AKI treatment.

Methods: Renal tubular epithelial cells were cultured in a low oxygen environment, then cocultured with MSC EVs or control medium for 48 h. BrdU and transferase-mediated dUTP nick-end labeling (TUNEL) staining were used to assess cell proliferation and apoptosis. Mice subjected to ischemia reperfusion were randomly divided into 4 groups, then injected with either phosphate-buffered saline (vehicle), EVs, EVs overexpressing oct-4 (EVs+Oct-4), and EVs not expressing Oct-4 (EVs-Oct-4). Blood creatinine (CREA) and urine nitrone levels were assessed 48 h and 2 weeks after injection. After ischemia reperfusion, renal tissues from each group were stained with TUNEL and proliferating cell nuclear antigen (PCNA) to determine the degree of apoptosis and proliferation. Masson trichrome staining was used to evaluate renal fibrosis progression. Snail gene expression was assessed using polymerase chain reaction (PCR).

Results: At 48 h after hypoxic treatment, TUNEL and BrdU staining indicated that the EVs+Oct-4 group had the least apoptosis and the most proliferation, respectively. Treatment with EVs overexpressing Oct-4 significantly decreased serum Crea and blood urea nitrogen levels and rescued kidney fibrosis, as indicated by the low proportion of Masson staining, high number of PCNA-positive cells, and low number of TUNEL-positive cells. PCR analysis indicated that Snail was most upregulated in the vehicle group and least upregulated in the EVs+Oct-4 group.

Conclusions: MSC EVs had a pronounced therapeutic effect on ischemic reperfusion injury-related AKI, and Oct-4 overexpression enhanced these therapeutic effects. Our results may inspire a new direction for AKI treatment with MSC EVs.

Keywords: Acute kidney injury; Extracellular vesicles; Human umbilical cord mesenchymal stem cells; OCT-4.